| The correct classification of prevailing bulk hydrometeor type within a
radar resolution volume is a challenge task even if a full set of
polarimetric radar observables is available. Indeed scattering and
propagation effects from the variety of hydrometeors present interact each
others and sometimes, if not often, tend to obscure the characteristic
signature of each weather radar target type. This consideration is enforced
when the atmospheric volume is sampled with a wavelength where both Mie
scattering effects and attenuation start to become relevant.
In this paper, we utilize the hydrometeor classification scheme developed at
the National Severe Storms Laboratory (USA). Briefly, the scheme uses a
fuzzy logic approach to combine different polarimetric variables and
environmental temperature in order to determine the most likely type of
prevalent hydrometeor in the radar volume. This means that the resulting
classification is based on two characteristics: the volume polarimetric
responses and the thermal value. The relative balance between these two is
managed through the coefficients in the fuzzy scheme. We have observed that
these parameters are crucial in order to get "physical reasonable result",
independently from the meteorological character of the event investigated.
Our work is based on a reduced set of polarimetric variables (Z and
ZDR) as input. Data used in this study were collected by a C-band radar over weather events ranging from convective to stratiform. |